1. Field of the Invention
The present invention relates generally to a resist residue remover for removal of resist residues occurring in semiconductor device or liquid crystal device fabrication processes. More specifically, this invention is directed to a resist residue remover used for removal of resist and other residues which occur in a process wherein a photoresist is coated on an electrically conductive metal or insulating film formed on a substrate, and exposed to light and developed to form a resist pattern thereon, and this resist pattern is used as a mask to selectively etch the metal or insulating film or implant ions for circuit formation, and an unnecessary portion of the resist is removed by ashing. According to the invention, such residues can be removed without any corrosion of the conductive or insulating film.
2. Description of the Background
For removal of resist residues in fabrication processes of semiconductor devices such as those of silicon and compounds such as GaAs and liquid crystal devices (LCDs), compositions comprising a main component mixed with an organic solvent, etc. have so far been used, said main component being selected from strong acids such as hydrochloric acid, sulfuric acid and nitric acid; hydrogen peroxide; ammonia; fluorides such as hydrofluoric acid and ammonium fluoride; and amines and hydrazines such as hydroxylamine, hydrazine and monoethanolamine.
All these compositions are hazardous chemicals or contain large amounts of dangerous materials such as organic solvents. With environmental protection in mind, therefore, some considerable protection measures are needed to secure safety, and carry out waste disposal, in semiconductor fabrication processes.
That is, remover compositions composed mainly of ammonium fluoride, which is in itself a terrible chemical, are used upon diluted with organic solvents such as N-methylpyrrolidone and dimethylformamide that are dangerous materials. Also, hydroxylamine, tetramethyl-ammonium hydroxide, monoethanolamine, etc. are in themselves organic materials or used in the form of compositions with other organic materials.
In semiconductor fabrication processes using such compositions as those containing large amounts of organic materials that are terrible chemicals or dangerous materials, therefore, some considerable safeguards are required for the purposes of securing the safety of work, and environmental protection.
For compositions containing much organic materials, the step for removal of resist residues must be followed by a rinsing step wherein rinsing must be carried out using a water-soluble organic solvent such as isopropyl alcohol, and N-methylpyrrolidone. However, this organic solvent is a dangerous material for which some safeguards or environmental protection measures are needed.
On the other hand, metals such as tungsten and titanium are now increasingly used for gate structures. However, this offers a problem in that a sulfuric acid aqueous solution of hydrogen peroxide (SPM) or an ammonia aqueous solution of hydrogen peroxide (APM) available for removal of resist residues cannot be used because of corroding the metals, resulting in breakdowns of the gate structures. With removers composed mainly of amines, on the other hand, it is difficult to remove resist residues that remain after ion implantation etching using phosphorus, arsenic, boron and other ions.
An object of the present invention is to provide a resist residue remover which enables resist residues occurring in semiconductor or liquid crystal fabrication processes, i.e., metal component-containing residues or implanted ion-containing resist portions remaining after dry etching to be removed without any corrosion of interconnecting wires or gate metals.
This object is achievable by the inventions recited hereinbelow.
(1) A resist residue remover which comprises an aqueous solution containing ammonium phosphate and/or condensed ammonium phosphate and having a pH ranging from 1 to 10.
(2) The resist residue remover according to (1) above, wherein said ammonium phosphate and/or said condensed ammonium phosphate have a concentration of 20% by mass or less as expressed in terms of total phosphorus concentration.
(3) The resist residue remover according to (1) or (2) above, wherein said condensed ammonium phosphate contains ammonium polyphosphate in which a polymerization degree thereof is n=2, 3, 4 or 5 and/or ammonium metaphosphate in which a polymerization degree thereof is n=3, 4 or 5.
(4) The resist residue remover according to any one of (1) to (3) above, wherein said pH is adjusted using at least one compound selected from phosphoric acid, condensed phosphoric acid and ammonia.
(5) The resist residue remover according to any one of (1) to (4) above, which further contains a surface active agent and/or a chelating agent.